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Tolerances for Spur and Helical Racks

AGMA 943-A22

AGMA 943-A22

ABSTRACT

This information sheet establishes a tolerance classification system relevant to manufacturing and conformity assessment of tooth flanks of a single piece spur or helical rack. It specifies definitions for rack flank tolerance terms, the structure of the flank tolerance class system, and allowable values.

 

FOREWORD

This information sheet establishes a tolerance classification system relevant to manufacturing and conformity assessment of tooth flanks of a single piece rack. It specifies definitions for rack flank tolerance terms, the structure of the flank tolerance class system, and allowable values.

AGMA 390.03 was published in 1973 and revised in 1980, and was a consolidation of several AGMA publications, including: 

AGMA 235.02 (1966), Information Sheet for Master Gears 

AGMA 239.01 (1965), Measuring Methods and Practices Manual for Control of Spur, Helical and Herringbone Gears 

AGMA 239.01A (1966), Measuring Methods and Practices Manual for Control of Bevel and Hypoid Gears

and parts of: 

AGMA 236.05 (ASA B6.11, June 1956), Inspection of Fine-Pitch Gears 

AGMA 390.02 (1964), Gear Classification Manual, originally published as AGMA 390.01 (1961)

Data was added in AGMA 390.03 for gear rack and fine-pitch worms and worm gears. The former AGMA 390.02 for coarse pitch and fine pitch spur, helical and herringbone gearing was enhanced to offer a single, compatible classification system. The tolerance identifier “Q” was added to indicate that the tolerances in 390.03 apply. If Q is not used as a prefix in the quality number, tolerances in AGMA 390.01 and 390.02 applied. 

ANSI/AGMA 2000-A88 was an update of those sections from AGMA 390.03 for parallel axis gears only. The other material in AGMA 390.03 on bevel and hypoid gears, racks and worm gearing were contained in AGMA 390.03a. Subsequently, the other material in AGMA 390.03a on bevel and hypoid gears and worm gearing was replaced by ANSI/AGMA 2009-A99 and ANSI/AGMA 2011-A98, respectively. 

This document is an update of AGMA 390.03a for racks. It features a new tolerance classification system V for elemental features and uses the existing R system for composite measurements.

The first draft of AGMA 943-A22 was created in August 2007. It was approved by the AGMA Gear Accuracy Committee in January 2022. It was approved by the AGMA Technical Division Executive Committee in February 2022.

 

SCOPE

This information sheet establishes a tolerance classification system relevant to manufacturing and conformity assessment of tooth flanks of a single piece rack. It specifies definitions for rack flank tolerance terms, the structure of the flank tolerance class system, and allowable values.

This document provides the manufacturer and purchaser with a mutually advantageous reference for uniform rack tolerances. Twelve flank tolerance classes are defined, numbered V3 to V14, in order of increasing tolerance. For composite measurements, twenty tolerance classes are provided, numbered R31 through R50 in order of increasing tolerance. Equations for tolerances are provided in 6.5. These tolerances are applicable to the following ranges:

3 mm ≤ LR ≤ 3500 mm

0.5 mm ≤ mn ≤ 70 mm

4 mm ≤ b ≤ 300 mm

β ≤ 45°

where 

LR       is the rack length;

mn     is the normal module;

b       is the face width; 

β       is the helix angle.

The measurement methods and tolerances are applied to a rack in the fixtured state that replicates the rack application.

 

NORMATIVE REFERENCES

The following documents contain provisions that, through reference in this text, constitute provisions of this information sheet. At the time of publication, the editions were valid. All publications are subject to revision, and the users of this information sheet are encouraged to investigate the possibility of applying the most recent editions of the publications listed.

ANSI/AGMA/ISO 1328-1, Cylindrical Gears – ISO System of Flank Tolerance Classification – Part 1: Definitions and Allowable Values of Deviations Relevant to Flanks of Gear Teeth

ANSI/AGMA/ISO 1328-2, Cylindrical gears — ISO system of accuracy — Part 2: Definitions and allowable values of deviations relevant to radial composite deviations and runout information

ISO/TR 10064-1, Code of Inspection Practice – Part 1: Measurement of Cylindrical Gear Tooth Flanks


Pages: 22

ISBN: 978-1-64353-117-5

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